To satisfy demands for wireless data traffic having increased since commercialization of 4th-Generation (4G) communication systems, efforts have been made to develop improved 5th-Generation (5G) communication systems or pre-5G communication systems. For this reason, the 5G communication system or the pre-5G communication system is also called a beyond-4G-network communication system or a post-Long Term Evolution (LTE) system.
To achieve a high data rate, implementation of the 5G communication system in an ultra-high frequency (mmWave) band (e.g., a 60 GHz band) is under consideration. In the 5G communication system, beamforming, massive multi-input multi-output (MIMO), full dimensional MIMO (FD-MIMO), an array antenna, analog beamforming, and large-scale antenna technologies have been discussed to alleviate a propagation path loss and to increase a propagation distance in the ultra-high frequency band.
For system network improvement, in the 5G communication system, techniques such as an evolved small cell, an advanced small cell, a cloud radio access network (RAN), an ultra-dense network, a device to device (D2D) communication, a wireless backhaul, a moving network, cooperative communication, coordinated multi-points (CoMPs), and interference cancellation have been developed.
In the 5G system, advanced coding modulation (ACM) schemes including hybrid frequency-shift keying (FSK) and quadrature amplitude modulation (QAM) modulation (FQAM) and sliding window superposition coding (SWSC), and advanced access schemes including filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) have been developed.
Meanwhile, as one of methods for supporting an improved data rate, a full-duplex communication scheme has been considered in which one node performs transmission and reception at the same time. The full-duplex communication scheme ideally improve capacity up to by twice the capacity of a half-duplex communication scheme where a time or frequency resource is orthogonally used to perform transmission and reception. However, the full-duplex communication scheme performs transmission and reception at the same time, causing strong self-interference.
FIG. 1 shows a probability of non-detection of a physical uplink control channel (PUCCH) signal with respect to the amount of a residual self-interference (RSI) after cancellation of self-interference in a general full-duplex communication system. Herein, as an example of the PUCCH signal, an ACK/NACK signal is assumed. As shown in FIG. 1, as the amount of RSI increases, the performance of detection of an HARQ ACK/NACK signal sharply degrades. If an UL control signal is damaged by self-interference, both DL transmission quality and UL transmission quality may not be guaranteed. Therefore, to apply the full-duplex communication scheme, it is important to secure UL control signal transmission from self-interference.
A separated antenna scheme, which is one of methods for cancelling self-interference, is a technique for enabling the use of the same frequency and time resources by spatially separating transmission and reception using multiple antennas. Another scheme, a shared antenna scheme uses the same antenna for transmission and reception, and cancels self-interference by using a circulator device. With the development of self-interference cancellation techniques, study has been conducted to apply full-duplex communication to a cellular system for capacity increase of a communication system. When a base station (BS) and a user equipment (UE) communicate with each other using existing half-duplex communication, a time resource or a frequency resource is divided for transmission, such that a transmitting UE and a receiving UE may not operate at the same time or may not use the same frequency resource. As a result, in spite of no interference between a transmitting node and a receiving node, an overall frequency efficiency degrades due to division of the resource. On the other hand, when the full-duplex communication scheme is used in the cellular system, the BS and the UE perform transmission and reception at the same time, increasing frequency efficiency, in spite of increase of self-interference and interference between UEs. Such a gain may be further improved if self-interference or interference between UEs may be effectively controlled, and to smoothly manage the cellular system, there is a need for a method for protecting an interference element according to a type and an importance of a signal transmitted by a UE or a BS.